1. Field of the Invention
The present invention relates to a system that precisely recognizes the position of an object which is too small to be marked, a positioning-system that recognizes the position of an object and positions the object to a predetermined place, and an object adjoining system and method in which positions of a plurality of objects are recognized, and the objects are positioned and then adjoined in a given relation to each other.
2. Description of the Related Art
As a method for recognizing the position of an object (object-position recognition), there is a method that performs recognition by using an image processing on the basis of its outer shape. In the position recognition using image processing, it is necessary to detect an image corresponding to an outer shape to be recognized in a captured image.
When performing the recognition for a center position of a hole made in the object, if an image is captured by an optical system having an angle of view, the captured image inevitably has that of a hole wall portion, which may cause deviation in recognized position of the hole edge on image basis. To address the problem, a method is applied in which the applicable target hole is limited to the round one, a captured image of a coordinate system is converted to that of a polar coordinate system and then a possible range of position for the hole edge is determined by circumferential brightness of its projection image. In the example of this method, the hole edge is determined to exist between where the brightness value is ten percent smaller than the maximum brightness value in the projection image and where the brightness value is ten percent larger than the minimum. In the possible edge range, each position of the edge on each line in radial direction is detected using a differential processing, so that a circle corresponding to the round hole is determined by applying the least squares method to the detected positions of the edge (Patent document 1: Japanese Patent Laid-Open No. 1997(H09)-42915).
Further more, there is a method that recognizes an object having a mirror-like surface or a concave/convex shape using image processing, in which uniform illumination that enables image processing is made on the object and its concave/convex portion as well, by the illumination using an illumination device configured with integrated means of epi-illumination and diffuse illumination, brightness of which are independently adjustable (Patent document 2: United States Patent Application Publication No. 2005/0238222, Japanese Patent No. 4122187).